1. Field of the Invention
The invention in general relates to TV sensor systems which move relative to a scene to be viewed, and particularly to a compensation arrangement therefore for systems wherein the ratio of velocity to distance to the scene is relatively high.
2. Description of the Prior Art
In survey and reconnaissance operations use is made of a TV sensor system for viewing a target area under investigation. The system is mounted on a carrier vehicle which moves over the area at a certain velocity V and at a certain altitude H.
For those applications where the V/H ratios are relatively high, there is an objectionable loss of resolution of the video picture displayed. The resolution loss due to motion has two primary causes. One is the actual smearing of the picture that occurs between TV frame readouts and the other is tube lag, an unavoidable property of the TV camera tube wherein residual signals remain on the tube's target element from frame to frame.
Moving mirrors, or a moving film is used in airborne photo-recconnaissance applications to maintain a point in the center of the scene motionless at the image plane. The arrangement prevents smearing during camera exposure time, however, the use of a mirror or TV camera motion for image motion compensation is difficult for TV use because of the fast deflection required at conventional TV rates.
In image intensifier hand-held directly viewed night vision devices, a magnetic field has been used for motion compensation. The arrangement, however, uses a plurality of gyroscopic pickoffs for supplying feedback signals, to compensate for the user's hand movement.
The present invention accomplishes image motion compensation electronically in a television sensor system wherein the V/H ratio is relatively high.